GENOTYPE, AGE, MUSCULAR STRENGTH AND MUSCLE MASS

描述（改编自申请人的摘要）： 力量和肌肉质量随年龄增长（肌肉减少症）和增益与力量 培训是有据可查的，但这些反应差异很大 在个体之间。环境因素，如 运动水平，不能解释个体间的巨大差异 在力量和肌肉质量观察与老化或力量训练。 这表明遗传因素可能至少占一部分 这些个体间的差异。看起来很好的基因 衰老和力量训练引起的肌肉变化的候选人 质量包括生长激素（GH），胰岛素样生长因子-I（IGF-I）， IGF-I受体，IGF结合蛋白（IGFBP）-2和4，肌生长抑制素，和 肌营养不良蛋白-糖蛋白复合物的组分。但具体 基因还没有被发现。因此，假设 年龄和力量训练对肌肉力量和肌肉的影响 质量受到这些关键骨骼的多态性变化的影响 肌肉相关基因位点为了检验这一假设， 在800名受试者的成年期内进行横断面测定 巴尔的摩老龄化纵向研究（BLSA）。所有这些 受试者将已经进行了力量测试，大多数（约600 受试者）将在本研究时进行肌肉质量测试 开始.基因型也将在100名受试者中确定， 完成了标准化的力量训练计划， 在这个实验室里进行纵向研究。在BLSA研究中，强度和 肌肉质量将通过一般线性模型程序进行分析， 以基因型、性别和年龄作为回归变量， 这些变量的相互作用。在力量训练研究中， 混合模型程序将与固定部分一起使用， 基因型、力量训练及其相互作用的影响。的 这项研究的潜在意义是，它可以确定受试者 容易出现肌肉减少症，并提供有关谁的信息 可能对力量训练干预最敏感， 扭转肌肉减少症的影响。

DESCRIPTION (Adapted from the Applicant's Abstract): Losses of muscular strength and muscle mass with age (sarcopenia) and gains with strength training are well documented, but these responses vary substantially among individuals. Environmental factors, such as differences in exercise levels, do not explain the large inter-individual differences in strength and muscle mass observed with aging or strength training. This suggests that genetic factors may account for at least a portion of these inter-individual differences. Genes that appear to be good candidates for aging- and strength training-induced changes in muscle mass include growth hormone (GH), insulin-like growth factor-I (IGF-I), IGF-I receptor, IGF binding protein (IGFBP)-2 and 4, myostatin, and components of the dystrophin-glycoprotein complex. However, specific genes have not been identified. Thus, it is hypothesized that the effects of age and strength training on muscular strength and muscle mass are affected by polymorphic variations at these critical skeletal muscle-related gene loci. To test this hypothesis genotypes will be determined cross-sectionally in 800 subjects across the adult life span from the Baltimore Longitudinal Study of Aging (BLSA). All of these subjects will have already been tested for strength and most (~600 subjects) will have been tested for muscle mass by the time this study begins. Genotypes also will be determined in 100 subjects who have completed a standardized strength training program in previous longitudinal studies in this laboratory. In the BLSA study, strength and muscle mass will be analyzed by general linear model procedures to fit the effects of genotype, gender, and age as regression variables and the interactions of these variables. In the strength training study, linear mixed model procedures will be used with the fixed portion containing the effects of genotype, strength training, and their interactions. The potential significance of this study is that it may identify subjects prone to early onset of sarcopenia and provide information about who might be most responsive to strength training interventions designed to reverse the effects of sarcopenia.